Gmail launched a new feature this morning designed to detect suspicious activity in your account and notify you when a suspicious login has occurred in your account.

Now, if it looks like something unusual is going on with your account, we'll alert you by posting a warning message saying, "Warning: We believe your account was last accessed from…" along with the geographic region that we can best associate with the access.

To determine when to display this message, our automated system matches the relevant IP address, logged per the Gmail privacy policy, to a broad geographical location. While we don't have the capability to determine the specific location from which an account is accessed, a login appearing to come from one country and occurring a few hours after a login from another country may trigger an alert.

If you see the warning and click to Show details and preferences, you'll see something like the image below:

...which prompts you to change your password immediately if something seems amiss. If it's a legitimate access—say you're traveling—you can simply click Dismiss and everything will go back to normal.